Hei.
If there was one stone, the damage should have a sharp "outbreak" definition, which propably results in a single long crack. Else, there might be a diffuse "outbreak" (I have difficulties finding the correct words and translation - reason: check "location" on bottom of post) resulting in several cracks. This is propably due to stress.
I remember when my Fiat Ritmo (Strada) broke down, I took it to a garage. They lifted it up, and the whole front window cracked into the shape of a spider, with cracks like the spiders feet around its oval shaped body. This was due to corrosion of the whole car - and therefore: stress cracked the window. (The Ritmo 70 then died, hanging there - we now have a "new" 130TC!)
Anyway, a stone may crack your window, but only when driving, at slightly high speeds also. When another car runs over a stone, it may get thrown UP and then you actually HIT it with your speed. The rocks seldom has any speed itself.
What's the difference between a rock and stone???
Morten.